This invention pertains to the field of wide angular aperture, tunable optical filters.
There is interest in producing narrow-band rapidly tunable filters. It is also desirable to have a filter that would allow scanning of object waves with 1cm.sup.-1 resolution while preserving all of the spatial information in the object image. There is a need to provide filters for analyzing radiation from laser-target interactions where the object wave radiation is emitted in an intense pulse which is time synchronous to a master laser pulse. A further area of interest for filters occurs when filtering object waves have very low intensities. Narrow angular aperture filters aggravate the low intensity problem by their inability to utilize all of the light incident upon the filter. A further problem with interference filters is that the central frequency of the pass-band depends on the angle of incidence of the beam because this changes the pathlength of the light through the device.